The overall goal of our Georgia State University School of Public Health Center of Excellence has been to pursue the concept that adverse social conditions, acting synergistically, worsen the health disparities between groups, and create increasing entrapment of people in their disadvantaged condition. The term syndemics has been used to describe such a social condition. Its elements involve personal risks, susceptibility to a variety of diseases and conditions, neighborhood and environmental factors, and large-scale social ills that permeate the lives of disadvantaged persons. The complex interaction of these factors is difficult to study directly. Rather, we have focused on health disparities as the metric for demonstrating the ill effects of the combined influence of these factors. Health disparities pose an interesting problem, however. On a large scale, they are obvious and, at least in the short term, seemingly immutable. On a small scale, with a focus on definable areas or on definable populations, disparities may not be appreciated, often for lack of small data. Thus, our overall goal of defining syndemic interactions has been tied to the theme of demonstrating actionable health disparities in specific groups or areas. The two pilot projects that we propose build on three threads that run through our Center of Excellence. First, an important source of health inequality arises from the built environment and environmental insults to which disadvantaged populations are subject. Second, these environmental issues need to be interwoven with social determinants and personal risks in order to understand their impact. Third, a major effort within our COE to develop more effective urban metrics can be brought to bear for examining a range of risks and determinants simultaneously. These projects focus on two important environmental risks-radon and excessive heat. Each uses existing monitoring data and proposes pilot gathering of other environmental data. Each will analyze the data sources in conjunction with existing data on social determinants and health outcomes using an Urban Health Index that we have developed. Each will provide pilot results that we believe will support the development of more effective urban policy for abatement of these risks. The goal of these proposed projects is to conduct pilot studies that will demonstrate disparities in susceptibility to environmental threats. Our objective is to show that well recognized environmental risks have not been sufficiently explored for their impact on vulnerable populations. The impact will be not only to raise awareness of such risks in low SES areas, but to provide solid evidence to decision makers for constructing remediation plans.